Photographic product containing zinc



June 4, 1968 E. g, LAN 3386325 PHOTOGRAPHIC PRODUCT CONTAINING zuc FiledDec. so, 1966 2 Sheets-Sheet 2 I 94 os s l l oo- 98 2 I /`|02 a o x 3all/l II4 '06 FIG5 A eou's Alkoline Solution Of Silver Hglde DevelperAnd Solvent And Dspersed Znc Silver Recepfive Stramm Support INVENTOR.

m 76. ::and

Ekam amd %M and Azam, s.. mm

ATTORNEYS United States Patent O 6 Claims. (Cl. 96-66) ABSTRACT OF THEDISCLOSURE Image-receiving elements and processing compositions for usein diffusion transfer photographic processes and containing finelydispersed Zinc are disclosed. Such Zinc dispersi-ons may be prepared byvacuum deposting zin-c upon an Organic plastic material and blending thematerials t-o disperse the zine within the Organic plastic material. Thefinely dispersed Zinc may be used as an antioxidant in photographicprocesses and products.

This application is a continuation-in-part of Ser. No. 249,922 filedJan. 7, 1963 (now U.S. Patent No. 3,295,972 issued Jan. 3, 1967), as acontinuation-in-part of Ser. No. 705,845, filed Dec. 30, 1957, and nowabandoned.

The present invention relates, in general, to novel uses of finedispersions of Zinc in photographic processes and products, and tomethods for producng fine dispersions of Zinc of exceptionally uniformcharacter.

A prma-y object of the present invention is to provide a process forproducing a dispersion of finely divided Zinc distributed uniformly inan external phase incompatible therewith, the process comprising thesteps of first vacuum depositing the Zinc onto a matrix materialmechanically possessing large surface area, and then blending thematerials in order to disperse the Zinc (internal phase material) in theexternal phase material.

Other objects of the present invention are: to provide a novelphotographic process involving subjecting an exposed silver halidestratum, in the presence of a fine dispersion prepared in the f-oregoingway, to a processing fluid for developing silver halide and forcooperating with the fine dispersion to form a transfer print; and toprovide a novel photographic process involving the use of a finedispersion of Zinc as an antioxidant.

Other o'bjects of the invention will in part :be obvious and will inpart appear hereinafter.

The invention accordngly comprises the several steps and the relationand `order of one or more of such steps with respect to each of theothers, and the scope of the application of which will be indicated inthe claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIGURE 1 is a broken-away, side elevation of an apparatus for performingsteps of a process of the present 30 invention;

FIGURE 2 is a cross section of the apparatus of FIG- URE 1, takensubstantially along the line 2-2;

FIG. 3 is a broken-away, side elevation of an apparatus for performingsteps of an alternative process of the present invention;

'FIGURE 4 is a perspective view of a Component of the apparatus of FIG.3;

FIG. 5 is a broken-away, side elevation of an apparatus for performingsteps of another alternative process of the present invention; and

FIG. 6 is a flow diagram showing exaggerated cross- &386,825 PatentedJune 4, 1968 sectional views of materials undergoing steps of aphotographic process of the present invention.

Generally, as indicated above, the processes of the present inventionherein disclosed involve vacuum depositng at least part of the material,i.e., Zinc, that is to constitute the internal phase onto a matrixmaterial mechanically possessing large surface area, and then blendingthe materials in order to disperse or to prepare to disperse theinternal phase material in at least part of the material that is toconstitute the external phase. The 'step of vacuum depositing involveseither evaporating or sputtering at pressures below microns of mercuryand usually within the range of from 0.1 to 100 microns of mercury,these pressures being produced by continuous evacuation to ensure therapid removal of any gases produced during the vacuum depositionprocess. The internal phase material is transmitted to the matrixmaterial in submicroscopic, e.g., molecular or ato-mic, form. The matrixmaterial, which may constitute at least a proportion of the externalphase, initially is in powder-like or sheet-like form for the purpose ofproviding large surface area per mass. Where the matrix material is toconstitute the external phase exclusively, the ultimate dispersion maybe produced from the coated matrix material by blending, for example, bymolding under heat or casting, spraying or flowing from solution. Wherethe matrix material is not to constitute the external phase exclusively,the matrix material, after being coated, may be `blended in any suitableway with the remaining materials of the external phase, for example, maybe dissolved in a solution already containing these remaining materials.The present invention provides a fiexible technique for providingdispersions in which the internal phase, the external phase or bothcomprise a plurality of different materials. Thus, one or more internalphase materials may be vacuum deposited on one or more matrix materialsand the resulting materials blended with one or more additionalmaterials to provide a dispersion of desired formulation.

FIGURE 1 illustrates an apparatus for evaporating an internal phasematerial 20 onto a matrix material 22 of large surface area per mass.Material 20, for example, is a metal in the form of a coating upon awire gauze and material 22, for example, is in the form of a finelydivided powder composed of-an Organic plastic. Powder 22 is containedwithin a cylindrical glass jar 24, one end of which closed at 26 and theother end of which is provided with an open mouth 28. Gauze 20 issupported by a mounting arm 30 extending through mouth 28 and carrier bya standard 32. Jar 24 rests upon a pair of rollers 34 and 36, the endsof which are journaled in hearing mounts 38 and 40. A motor 42 isprovided for rotating rollers 34 and 36 through gearing 37 in order tocause rotation of jar 24, which is prevented from moving longitudinallyby circular flanges 44 at the ends of the rollers. As shown, electricalleads 46 and 48 are connected to the opposite extremities of gauze 20 inorder to transmit a suitable electric current through the gauze from apower supply (not shown). In operation, a sufficient current istransmitted by leads 46 and 48 through gauze 20 for generatingsuflicient heat to cause rapid evaporation of the coating of gauze 20.At the same time, motor 42 causes rotation of rollers 34 and 36 so thatpowder 22 is continuously agitated by movement of the inner surfaces ofjar 24, as Well as a plurality of ribs 50 projecting inwardly from theinner surfaces of the jar. The apparatus, including jar 24, is mountedon a base plate 52 and enclosed by such means as a glass cylinder 54 anda cover plate 56. O-ring gaskets 57 hermetcally seal glass cylinder 54between base plate 52 and cover plate 56. A pump (not shown)continuously exhausts the region defined by base plate 52, glasscylinder 54 and the cover plate 56 through a conduit 60. Powder 22, as aresult,

becomes coated with the metal which initially is part of gauze 20. Thecoated powder then is heated and molded or dissolved and cast to form atwo-phase solid comprising the metal of ganze 20 as an internal phaseand the plastic of powder 22 as an external phase.

An alternative method for producing a dispersion in accordance With thepresent invention is shown in FIGS. 3 and 4 as involving thevolatilization of a quantity of an internal phase material 62, forexample, a metal within an electrically heated crucible 58, typicallycomposed of tantalum, above which is located an extremely thin sheet ofa matrix material 70 in the form of an Organic plastic. As shown,crucible 58 is carried by a mount 72 having a depending shaft 74, whichis adjustably secured in an upstanding sleeve 76 by a manuallycontrolled screw 78. Sleeve 76 is carried by a base plate 77. Sheet 70is carried by a pair of supports 80, in turn mounted under a cover plate82. The region defined by the base plate 77 and cover plate 82 isenclosed by a glass cylinder 84, which is hermetically sealed betweenthe base plate and the cover plate by a pair of upper and lower O-rings86. In operation, the region defined by base plate 77, glass cylinder 84and cover plate 82 is continuously exhausted by a pump (not shown)through a conduit 88 and crucible 58 is heated by a relatively largecurrent supplied through a pair of leads 90 and 92. The coated sheet 70then is heated and molded or dissolved and cast to form a two-phasesolid comprising metal 62 as an internal phase and the plastic of sheet'70 as an external phase.

Another alternative method for producing a dispersion in accordance withthe present invention is shown in FIG. as involving so called cathodesputtering. When an electrical discharge is passed between electrodesunder low gas pressure, the cathode electrode is slowly disintegratedunder :bombardment by ionized gas molecules. The disintegrated materialleaves the cathode surface either as free atoms or in chemicalcombination with the residual gas molecules. Some of the li beratedatoms are condensed on surfaces surrounding the cathode.

As shown in FIG. 5, in accordance with the present invention, amaterial, for example, a metal to form the internal phase is sputteredfrom a cathode 94 onto a sheet 96 of a matrix material, for example, anOrganic pastic that is to form the external phase. Sheet 96 is carriedby a mount 98 having a depending shaft 100, which is adjustably securedwithin an upstanding sleeve 102 by a manually controlled screw 104.Upstanding sleeve 102 is supported upon a base plate '106. Cathod'e 94is carried under a cover plate 110 by a pair of insulatin g spacers`&08. The region defined ?by base plate 106 and cover plate 110 isenclosed by a metallic cylinder 1'12, which is hermetically sealedbetween the base plate and the cover plate by a pair of upper and lowerO-'ings 114. In operation, the region defined by base plate 106,cylinder 112 and cover plate 1,10 is continuously exhausted by a pump(not shown) through a conduit 116. A voltage capable of producingsputtering within an atmosphere at the pressure determined by the pumpis applied between cylinder 112 and cathode 94 which, when so excited,transmits atomic or molecular particles to sheet 96. The coated sheet 96then is heated and molded or dissolved and cast to form a two-phasesolid comprising the metal from cathode 94 as an internal phase and theplastic of sheet 96 as an external phase.

As indicated above, although the process of the present invention hasgeneral utility, it is specifically applicable to certain products thatare particularly useful in photographic difusion transfer processes. Ina silver diffusion transfer process, for example, a photoexposed silverhalide material and a silver precipitatin g material are subjected to anaqueous alkaline solution of a silver halide developing agent and asilver halide solvent. The developing reduces exposed silver halide tosilver and the solvent reacts with unreduced silver halide to form acomplex silver salt that migrates to the silver precipitating materialwhere it is reduced to form a visible silver print. It has been foundthat zinc is particularly efiective in such processes, particularly whendispersed in accordance with the present invention. Vacuum depositionpermits close control of particle size and thus facilitates the use ofparticle sizes most suitable for activity and the desired level ofcoverng power.

Plastc materials of which the external phase may be composedadvantageously are cellulosics such as carboxymethyl cellulose andcellulose acetate hydrogen phthalate, vinyls such as polyvinyl alcohols,nylons such as polyhexamethylene adipamide, and natural polymers such asagar, casein, gelatin, etc. One may also use plastics which are normallyimpermeable or only slightly permeable to the photographic processingsolution, provided that such plastics may be rendered permeable by atreatment, e.g., acid hydrolysis, which does not adversely afect thedispersed zinc. When the Vacuum deposition is efected by evaporation,temperatures ranging from 300 to 15 00 C., in accordance with therequirements of the material being evaporated, and pressures below 0.5micron of mercury are common. When the Vacuum deposition is etfected bycathode sputtering, voltages of the order of 5 to 10 kilo volts, andpressures of from 10 to 20 microns of mercury are common.

FIG. 6 illustrates a difiusion transfer process in accordance with thepresent invention. A silver print is formed in straturn when a silverhalide processing fluid 148 is spread in a uniformly thin layer betweenadjacent superposed surfaces of silver-receptive stratum 150 and aphotoexposed photosensitive silver halide emulsion 146 that is coatedupon a support 144. Processing fluid 148 contains an alkaline aqueoussolution of a silver halide developing agent, a silver halide solvent,and finely dispersed zinc. The spreading, for example, may beaccomplished by advancing the sheets, together with the fluid, between apair of pressure-applying rollers. Further details of processes of thistype are disclosed in U.S. Patent No. 2,543,181, issued to Edwin H. Landon Feb. 27, 1951, and in many other patents. Examples of suitable silverprecipitating agents may be found in the aforementioned parentapplication, now U.S. Patent No. 3,295, 972, which disclosure is herebyincorporated.

Photosensitive stratum 150 may contain' one or more of the silverhalides, of which silver chloride, silver bromide and silver iodide areexamples, dispersed in a suitable protective colloidal material, forexample, gelatin, agar (albumen, casein, collodion, a cellulosic such ascarboxymethyl cellulose, a vinyl polymer such as polyvinyl alcohol or alinear polyamide such as polyhexamethylene adipamide. Examples ofspecific formulations of conventional emulsions suitable for such useare described in T. T. Baker, Photographc Emulsion Technique, AmericanPhotographic Publish'ng Co., Boston, 1948, ch. IV.

suitable silver halide developing agents are: benzene derivatives havingat 'least two hydroxyl and/or amino groups substituted in ortho or paraposition on the benzene nucleus, such as hydroquinone, amidol, metol,glycin, p-aminophenol and pyrogallol; and hydroxylamines, in particular,prirnary and secondary aliphatic and aromatic N-substituted orfl-hydroxylamines which are soluble in aqueous alkali, includinghydroxylarnine, N-methyl hydroxylamine, N-ethyl hydroxylamine, andothers described in U.S. Patent No. 2,857,276, issued Oct. 21, `1958, inthe name of Edwin H. Land et al. suitable silver halide solvents forthese dispersions are: conventional fixng agents such as sodiumthiosulfate, sodium thiocyanate, ammonium thiosulfate and othersdescribed in the aforementioned U.S. Patent No. 2,543,181; andassociations of cyclic imides and nitrogenous bases such as associationsof barbturates or uracils, and ammonia or amines, and other associationsdescribed in U.S. Patent No. 2,857,274, issued Oct. 21, 1958, in thename of Edwin H. Land et al.

In silver difusion transfer processes, the processing compositionfrequently contains sodium sulte, which functions as an antioxidant tomaintain the developing agent in the reduced state. This sodium sulfite,however, undesirably tends to harden the gelatin with which it comes incontact. It has been found that such sodium sultflte may be replaced byzinc, dispersed in accordance with the present invention, which has nohardening effect on gelatin but which serves as an effectiveantioxidant. FIG. 6 shows an assemblage comprising, in sequence, asupport 144, a silver halide emulsion 146, a silver-receptive stratum150' and a support 152. Processing composition 148 contains dispersedzinc as an antioxidant, as illustrated by the following example.

Example Processing composition 148 having the following formulation:

Parts Water 1860 Sodium carboxymethyl cellulose `119 Dispersed zinc 3Sodium thiosulfate 14.5 Hydroquinone 52 Diethylamine 10 0 was preparedin the following manner: a dispersion of zinc in aqueous carboxymethylcellulose is prepared by evaporating 10 parts of zinc onto 400 parts of20 mesh carboxymethyl cellulose powder. Next, 121 parts of the resultingproduct is dissolved in 1860 parts of water. Then the hydroquinone,sodium thiosulfate and diethylamine are added, care being effected toprevent evaporation of the diethylamine. The dispersed zinc serveseffectively as an antioxidant while the processing fonmulation isstored, and does not interfere with the silver transfer process efectedby the composition when used.

The proportions of the ingredients in the processing fluids may bevaried within wide limits, as is well known in the art.

Where the zinc is incorporated in the processing solution, care shouldbe exercised to avoid the use of alkali metal hydroxides or otherreagents which would tend to form zinc oxide, thus reducing theantioxidant activity of the dispersed zinc. Organic reagents, andparticularly aliphatic amines, have been found effective to provide therequisite alkalinity without attackng the zinc.

It has been shown above that a dispersion of zinc may be effectivelyemployed as an antioxidant in a photographic processing composition. Theantioxidant properties of such a dispersion of zinc also may beeffectively utilized in photographc sheet components, e.g., as a layerin an image-receiving element, said zinc dispersion being adjacent,i.e., in antoXidant relationship, to an imagewise distribution ofimage-forming components, e.g., dye developers, which image-formingcomponents are susceptible to oxidation. The quantity of zinc so used isvery small, and should not introduce undesirable color or opacity.

Since certain changes may be made in the above products, processes andcompositions without departing from the scope of the invention hereininvolved, it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

What is claimed is:

1. A photographic developer composition comprising an aqueous solutionincluding an aliphatic amine, an Organic plastic material, a silverhalide solvent, a silver halide developing agent, and finely dispersedzinc, said solution being free of alkali metal hydroxides or otherreagents which would tend to form zinc oxide.

2. A photographic developer composition as defined in claim 1, saidfinely dispersed zinc being formed by the steps of vacuum depositingzinc upon an Organic plastic material presenting a large surface areaand mixing said 10 vacuum deposited zinc and said organic plasticmaterial with a solvent for said Organic plastic material, said solventbeing a nonsolvent for said zinc, thereby dissolving said Organicplastic material and forming a fine dispersion comprising said vacuumdeposited zinc as the discontinuous phase and said solvent and saidOrganic plastic material as at least part of the continuous phase ofsaid dispersion.

3. An image-receiving element for use in diffusion transfer processesand comprising at least a support and an image-receptive layer carriedby said support, said imagereceiving element including a small buteffective amount of finely dispersed zinc so positioned as to beeffective as an antioxidant for image-forming components present in saidimage-receiving element.

4. An image-receiving element for use in ditfusion transfer processesand comprising at least a support and an image-receptve layer carried bysaid support, said image-receiving element including a small buteffective amount of finely dispersed zinc so positioned as to beeffective as an antioxidant for image-forming components present in saidimage-receiving element, said :finely dispersed zinc being formed by thesteps of vacuum depositing zinc upon an Organic plastic materialpresenting a large surface area and mixng said vacuum deposited zinc andsaid Organic plastic material with a solvent for said Organic plasticmaterial, said solvent being a nonsolvent for said zinc, therebydissolving said Organic plastic material and forming a fine dispersioncomprising said vacuum deposited zinc as the discontiruous phase andsaid solvent and said Organic plastic material as at least part of thecontinuous phase of said dispersion.

5. An image-receiving element as defined in claim 3,

wherein said image-forming components are dye developers. 6. The methodof formng a fine dispersion of zinc,

References Cited UNITED STATES PATENTS 2,6*8 6,7l-6 8/ 1954 Land 96-292,69l,58*8 1 0/1954 Henn et al. 96-66.4 2,7 09,663 5/'19-55 McLean117-107.1 2,839,37-8 6/195'8 McAdow 96--29 2,98l,623 4/ 1961 Burgardt etal. 96-66r4 NORMAN G. TORCHIN, Primary Exam'ner.

J. P. BRAMMER, Assistant Exam'ner.

